Question

What additional information do you need to prove ... by SAS?

Answer 1

Answer: B (∠ACB≅∠ACD)

Explanation:

To prove congruency with SAS, you already have 2 sides, the marked congruent sides (BC≅CD) and AC≅AC because they are a shared side. You just need an included angle inbetween, which is

∠ACB and ∠ACD